The use of liquid natural gas (LNG) for powering movable machines is becoming increasingly popular. Among other things, LNG engines have a reduced carbon output and thus are viewed as more environmentally friendly than conventional diesel and other internal combustion engines powered by gasoline. In addition, given the prevalence of LNG (primarily methane), the cost associated with such fuel is lower than other fuel products and thus consumer demand for such machines is increasing. LNG machines can not only be used to power movable machines such as automobiles for over the highway use, but also to power many work machines used in industrial, construction, and agricultural settings such as, but not limited to, dump trucks, loaders, excavators, and the like.
While effective, LNG powered machines are currently not provided without difficulties. For example, for storage of the liquid natural gas onboard a machine, a specialized fuel tank needs to be provided. Such tanks include an inner chamber or tank which is cryogenically cooled to a temperature at which the natural gas is maintained in liquid form. For example, such tanks often need to be cooled to −160° C. or less. In order to protect that inner tank from damage, and to assist with insulating the inner tank from heat loss, an outer tank is often provided around the inner tank with a vacuum insulation layer being provided therebetween.
With conventional movable machines, the ING tanks are fixably mounted to the outside frame of the machine. For example, rigid mechanical brackets may extend from the frame and be attached to the fuel tank. In so doing, the outer tank is exposed to vibration transmitted to the tank during the normal course of operation of the machine. As a result of the transmitted vibration and shock loads and inner structure damage that may result from such loading, the inner tank may not be able to be maintained at the low temperature desired, or if it is able to maintain such a temperature, can do so only at a lesser efficiency than prior to the damage. As liquefied natural gas takes up about 1/600th the volume of gaseous natural gas, if the lower temperature cannot be maintained, the tank will be subjected to elevated internal pressures and will vent to atmosphere.
Such damage is particularly likely with movable machines subjected to very large vertical loads. For example, with a large mining truck (LMT) used in large scale mining operations, the payload of such LMTs may be upwards of 400 tons. In order to efficiently load such trucks, loaders are often provided with a lifting capacity of 130 tons or more so as to ensure loading of the truck within three passes. By dumping 130 ton loads into such trucks, the trucks are subjected to extreme vertical loads and in so doing so are the liquid natural gas storage tanks rigidly attached thereto. With conventional LNG storage tank mounting systems, no dedicated structure of system is specifically provided to enable the tank to handle such vertical loads and thus the 130 ton load exerted against the trucks accelerates the truck rapidly enough to induce large loads against the ING storage tank. Accordingly, it can be seen that a need exists for a liquid natural gas storage tank mounting system for movable machines which is better able to isolate the tank from such large vertical loads.